Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 39891e79d79ef98c…

MALICIOUS

RTF / .DOC

1.74 MB
MD5: afae80c4289421c98dfacc37cf3708cd SHA-1: 8ba2d8b75e728ef5274fd309883cfe4ad9658778 SHA-256: 39891e79d79ef98cb707cbbe80f3eb7e19b972b19cd71563961aef22cad5be4f
240 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: Malicious File T1566.001 Phishing: Spearphishing Attachment T1059.001 Command and Scripting Interpreter: PowerShell

The sample is an RTF document containing OLE object data, specifically related to Equation Editor. Critical heuristics indicate a likely exploitation of CVE-2017-11882, a known vulnerability in Microsoft's Equation Editor. This vulnerability is often used to deliver a second-stage payload. The presence of large amounts of hex-encoded data within the OLE object further suggests the hiding of a malicious payload. The attack pattern is consistent with a spearphishing attachment designed to exploit this vulnerability upon opening.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1816KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001eb5.bin
7282082d1c3571256835d662b3ea7f3e3cfb259a72aa06ef0f4e993cb97de170		 rtf-objdata-decoded RTF \objdata at offset 0x1EB5 908497 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.